This project deploys a range of structural techniques to examine normal brain by light microscopic techniques. This project has been engaged in exploring various live brain preparations suitable for these purposes. Success has been achieved with a new approach to culturing hippocampal slices. Their typical laminar organization and most of their thickness can be maintained for up to 12 weeks by culturing them at the interface between air and culture medium. Structural and electrophysiological studies of the slices from different ages have been investigated. Within containing a number of sERs and almost no spines. Extracellular field EPSP's (fEPSP) amplitude was 3.5+/-1.1 mV and tetanic stimulation (100Hz, 1sec) caused no LTP. At 3 weeks, spines were present in large heterogeneity, fEPSP amplitude was 5.6+/-0.9 mV, and tetanic stimulation caused LTP in 63% of the slices. At 5 weeks, spine density was higher, but no significant increase in the fEPSP amplitude or ability to produce LTP was observed. The ability to express LTP appeared to be correlated with the appearance of the spines. Ultrastructural and the effect of various kinds of chemicals which control synaptic activities will be investigated.